The cytoarchitecture and fine structure of seven cortical tubera were studied by means of camera lucida drawings and Golgi sections in the coronal, sagittal, and tangential planes. Varied structural disorganization was observed in different tubera. Cytoarchitectural study revealed the absence of laminar and columnar cortical organization, whereas Golgi's method showed abnormal neuronal orientation and distribution. Pyramidal neurons manifested malrotation and orientation of the apical dendrites in aberrant directions. Large numbers of stellate cells in addition to medium-sized and small pyramids predominated in the intermediate and deep regions of the tubera. A generalized but focally accentuated disorder of cell migration and neuronal organization is postulated.